Modern oil field operators demand access to a great quantity of information regarding the parameters and conditions encountered downhole. Such information typically includes characteristics of the earth formations traversed by the borehole and data relating to the size and configuration of the borehole itself. The collection of information relating to conditions downhole, which commonly is referred to as “logging,” can be performed by several methods including wireline logging and “logging while drilling” (LWD).
In wireline logging, a probe or “sonde” is lowered into the borehole after some or all of the well has been drilled. The sonde hangs at the end of a long cable or “wireline” that provides mechanical support to the sonde and also provides an electrical connection between the sonde and electrical equipment located at the surface of the well. In accordance with existing logging techniques, various parameters of the earth's formations are measured and correlated with the position of the sonde in the borehole as the sonde is pulled uphole.
In LWD, the drilling assembly includes sensing instruments that measure various parameters as the formation is being penetrated, thereby enabling measurements of the formation while it is less affected by fluid invasion. While LWD measurements are desirable, drilling operations create an environment that is generally hostile to electronic instrumentation, telemetry, and sensor operations.
In these and other logging environments, measured parameters are usually recorded and displayed in the form of a log, i.e., a two-dimensional graph showing the measured parameter as a function of tool position or depth. In addition to making parameter measurements as a function of depth, some logging tools also provide parameter measurements as a function of azimuth. Such tool measurements have often been displayed as two-dimensional images of the borehole wall, with one dimension representing tool position or depth, the other dimension representing azimuthal orientation, and the pixel intensity or color representing the parameter value. See, e.g., B. Montaron, U.S. Pat. No. 5,519,668.
Recently, however, improved logging tools have been developed that can measure one or more formation parameters as a function of distance from the borehole axis, as well as depth and azimuth. See, e.g., M. Bittar, U.S. patent application Ser. No. 11/835,619, entitled “Tool for azimuthal resistivity measurement and bed boundary detection”. Such additional information would provide very helpful insight to drillers and other users of log information. However, as tool measurements extend further into the formations surrounding the borehole, the traditional telemetry and data presentation methods are increasingly unable to meaningfully convey such additional information.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular illustrated embodiments, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.